1. Field of the Invention
The invention relates to a custom fitting assembly for a helmet equipped with a protective hood. The system is particular suited for use with helmet mounted devices which support military air and ground operations.
2. The Prior Art
In general, helmets are designed to meet requirements for comfort, stability, and head impact protection during flight, egress and ejection, and to fit an anthropometric range of heads. With the advent of helmet mounted devices (HMDs) an increased demand for optical stability was required to keep the HMD in the operator""s field of view. This created various designs of inner liners and improved suspension systems to meet the comfort, stability and weight bearing requirements of the many HMDs.
Improvements in electro-optics technologies promised to transfer aircraft mounted head up displays and HMD imagery to the inner surface of the helmets visor or to other optical display combiner or device. With new Helmet Mounted Display (HMD) technologies comes a new and even tighter requirement for optical stability. Current helmets have been used to launch these new technologies with little success. The weights and center of gravity of new HMD systems displace the helmet out of the xe2x80x9ceyeboxxe2x80x9d thereby negating the HMD""s operational effectiveness as well as causing aircrew fatigue, neck strain, and during ejection possible severe injury and death.
An example of a prior art design is described in U.S. Pat. No. 5,584,073. A serious drawback with such platform is that to achieve a high level of stability, the suspension had to be tightened to the point of wearer discomfort. While the suspension system was tight it still swayed under xe2x80x9cGxe2x80x9d loading with HMD weights. Due to the narrow headband, the load bearing areas around the head created numerous areas of discomfort, known as xe2x80x9chot spotsxe2x80x9d. Additionally, each HMD system requires exact and repeatable placement of the image in front of the wearer""s eyes, which must be maintained during the entire mission and over many missions. Designers concluded that meeting such criteria with existing systems could not be practically achieved and would require an impractical number of helmet sizes to properly fit a large anthropometric head population.
Accordingly, it would be desirable to provide an inner helmet assembly in just a few sizes which could be easily custom-fitted to military personnel for use with various outer helmet systems for a variety of modern combat applications. Such an inner helmet would figuratively lock onto the wearer""s head thereby insuring reproducible alignment of the xe2x80x9ceyeboxxe2x80x9d to the eventual HMD.
It is therefore a primary object of the invention to provide a helmet fitting assembly in one or two sizes with custom-fitted inserts that can be adapted to various helmets.
It is a further object of the present invention to allow easy positioning of the helmet with positive locking devices.
It is yet another object of the present invention to provide an insert which is molded or formed in situ to conform to a portion of the wearer""s head.
It is still another object of the present invention to equip the helmet with a hood that provides protection against chemical agents and biological agent, as may occur during chemical or biological warfare or industrial accidents.
These and other related objects are met by providing a semi-rigid suspension system of independent components which contacts the head over large surface areas. The system includes a custom-contoured component and positive lock components which cooperatively allow repeated engagement of the desired design eye position.
The preferred embodiment of the system revolves around an inner helmet comprising a front forehead dome and side sections. A semi-rigid rear panel engages the wearer""s nape and has adjusting straps which extend generally forwardly to engage positive locking, clips located on the inner helmet side sections. The inner helmet is positioned in the fore and aft directions by the rear panel adjusting straps. A contoured pad then supports the forehead dome on the user""s forehead. The contoured pad includes an inner comfort layer, a primary layer which is custom fitted in situ, and an outer impact absorbing layer. Because the primary layer is essentially a mold of the wearer""s forehead it always seats in the same position.
A semi-rigid crown pad has adjusting straps which extend generally downward to engage positive locking clips located on the inner helmet side panels. The inner helmet assembly is suspended from the crown pad via the straps which are adjusted to bring the inner helmet to the desired vertical position. The inner helmet is restricted from upward movement by a chin strap or breathing mask.
The components of the helmet fitting assembly are adjusted along the horizontal and vertical axes to position the wearer""s eyes in the proper orientation and distance from the ultimate display. In use the helmet fitting assembly also resists forward rotation caused by the weight of the display systems located in front of the wearer""s forehead within the helmet. Forward rotation is characterized by the forehead dome sliding down while the rear portion of the helmet rides up. These forces are resisted by the brow pad which is molded to a particular part of the forehead, the nape panel, and by the chin strap or breathing mask which opposes any tendency of the rear part of the helmet to pivot away from the wearer""s chin.
It can be seen that we have met the various objects of the invention by providing a custom molded insert which complements the positive lock components used for alignment. The semi-rigid crown pad and nape panel are strong, lightweight and conformable to individual sizes and shapes. All inserts are designed to distribute weight and stresses over large surface areas avoiding sensitive regions of the head. The inserts work in conjunction with the chin strap or breathing mask and nape strap to resist pivoting forces thereby locking the helmet in its desired position.